The National Capital Authority has from today started six weeks of public consultation on the proposed memorials being positioned either side of the northern end of Anzac Parade.

The ultimate decision on whether the memorials can go ahead will be left to the Canberra National Memorials Committee headed by the Prime Minister.

The proposed 20m-high memorials originally had an approved design and site allocation at Rond Terraces at the foot of Anzac Parade.

Following a public outcry about the size and location of the monuments, their proponents, a group called the Memorials Development Committee, reduced the design of the monuments from 20m to 15m.

National Capital Authority chief executive Gary Rake said yesterday the proponents then wrote to the authority in mid-February to ask if it would consider a change of location for the memorials to two vacant sites either side of the northern end of Anzac Parade.

The NCA board agreed to put that proposal to the community and for the authority to also conduct a heritage and cost assessment. It would forward that advice, including the outcome of the consultation, to the Canberra National Memorials Committee for a decision. The authority is not a member of the committee.

Mr Rake said it was a significant step as the community outcry to date was about the public not getting a say on the previous location and design.

He said the memorial's existing design was a ''starting point'' but might not be dumped altogether.

''The current consultation process gives the community an opportunity to comment separately about the proposed site and any changes needed to make the monuments suitable for the site,'' he said.

Mr Rake said the authority had already advised the proponents that the design would have to meet the guidelines to commemorative works in the national capital which put a 12m height limit on Anzac Parade.

By comparison, the Australian Vietnam Forces National Memorial, which is already on Anzac Parade, is just under 12m.

Mr Rake said there also had to be an examination of whether the memorials could be positioned on Anzac Parade in the shadow of the Australian War Memorial.

''The commemorative guidelines say a proposal can't duplicate any existing commemorative sites but I note [on Anzac Parade] we have memorials to the Korea War, the Vietnam War and we're going to have one to the Boer War … I think there is potential for them to co-exist,'' he said.

Mr Rake said the authority would also, if necessary, make a referral to the federal environment department for the memorials to be assessed under the Environment Protection and Biodiversity Conservation Act.

The public consultation will continue until May 11. Comments can be made via www.nationalcapital.gov.au.